Bitumen is a dark-brown to black sticky material, solid or semi-solid in consistency, in which the primary constituents are a mixture of paraffinic and aromatic hydrocarbons and heterocyclic compounds containing sulfur, nitrogen and oxygen. In view of emerging need to improve bitumen properties, the use of chemical additives, particularly Polymers, is currently a much investigated subject.
In recent years, one of the important developments in the field of alternate application of virgin or used plastic/rubber material (mainly SBS and EVA type), is their use in making Polymer/Rubber Modified Bitumen (PMBs/RMBs) as value added product of Bitumen. Presently, PMBs/RMBs are used in huge quantities in making road highways infrastructure. PMBs/RMBs offer some definitive advantages over conventional bitumen such as lower susceptibility to daily and seasonal temperature variations, higher resistance to deformation at elevated pavement temperatures, better age resistance properties, better adhesion, less cracking even in heavy traffic conditions etc. The use of PMBs/RMBs, in India, has just begun during last decade particularly under highway development program.
Disposal of plastic material in general and PET based products like bottles for water/soft drinks etc., in particular, is one of identified factor for current pollution. Global efforts are underway, to recycle PET through both chemical and mechanical routes. Unfortunately, under mechanical recycling route, in particular, many prior art reported processes are not efficient and the quality of derived product remains questionable for recycling purposes.
On the other hand, “chemical recycling” which includes depolymerization of PET chains has been widely mentioned in the prior art. Five major approaches such as Glycolysis, Alcoholysis, Hydrolysis, Saponification and Aminolysis have been reported in several scientific literatures.
In aminolysis route our approach consisted of subjecting PET and amines such as ethanol amine, polyamine to temperature conditions from about 100° to 200° C. both under catalytic and non-catalytic conditions. PET on decomposition, as reported in our earlier patent (Application number: PCT/IB2013/050974), converts into product or product mixtures which are mainly terephthalamide derivatives.
One of the major challenge and a desirable approach in the aminolysis reaction is to develop products that can be used on an industrial scale. In our earlier patent (Application number: PCT/IB2013/050974) we have explored the process for utilization of terephthalamide synthesized from PET via aminolysis reaction as an anti-stripping agent for bitumen.
Lee, Sang-Yum; recently showed that the dimethylphenol (DMP) was added to the neat asphalt and polymerization carried out autonomously, without adding any external catalyst for the polymerization, only with oxygen molecules in the air. The polymer produced in the asphalt was polyphenyleneoxide (PPO) and it enhanced the mechanical properties of the asphalt.
EP 0561471 A1 discloses the bituminous composition comprising, block copolymer and conjugated diene and an acrylic monomer such as an alkyl methacrylate to form PMB. WO 2012007418 A1: discloses a Polyurethan-/Polyisocyanurat polymer obtainable from the reaction of an isocyanate-terminated with POLYOL outside of bitumen and then blend with bitumen. EP 0667886 B1 describes bituminous composition comprising a bituminous, conjugated diolefin and an acrylic monomer of a polyfunctional amine having at least two amino groups.
There arise needs to provide a process to utilize waste PET, which is a threat to environment and is available commercially in different physical forms, for conversion into industrially useful additive for bituminous product.